The present invention relates to a device for measurement of body motion. More particularly, the present invention relates to a platform assembly for use in measuring the loaded axes of the foot.
Apparatus such as goniometers have been known in the art for measuring the ranges of motion of body joints. However, no prior apparatus has been available commercially for measuring the loaded joints of the foot when loaded with full body weight in an in vivo condition.
By the present invention, there is provided a universal platform device on which the ankle (talo-crural) and subtalar (talo-calcaneal) joint axes can be located in the weight bearing foot. The device of the present invention provides simple effective biofeedback, i.e., rotation of a joint without other forces or motion on the leg, to aid the subject with the result that the device is extremely easy to use.
The platform assembly device of the present invention allows rotation of the above described joint axes about an aligned fixture axis in order to study the functions of the foot including measurements of the ranges of motion of the axes.
Since previously there was no commercially available means of measuring the loaded axes of the foot, a fixture was required to be designed and constructed to carry out such measurements. The universal platform of the present invention allows an internal axis to be determined by lining up the machine axis with an anatomical axis. By monitoring the leg motion while rotating the platform, the machine is adjusted so that the two axes are co-linear. When the axes are aligned, the universal platform can be rotated without causing leg motion. In this manner, the hypothesis which holds that only the talo-calcaneal joint behaves as a true axis under load can be proved.